Apparatus and method for filtering liquid particles from inspiratory gas flow of a patient breathing circuit affiliated with a ventilator and/or nitric oxide delivery system

ABSTRACT

The present disclosure relates to a filter apparatus for filtering liquid from a gas, the apparatus having a first housing having a gas inlet and a gas outlet; a first filter media disposed in the first housing; a second filter media disposed in the housing; and a second housing forming a first collection basin disposed in the flow path between the first filter media and the second filter media, so that a path is defined for the gas flowing from the inlet, through the first filter media, past the collection basin, through the second filter media, and to the outlet. The present disclosure also relates to a method of passing a gas through a coalescing filter media and through a hydrophobic filter media.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/446,110, filed Mar. 1, 2017 which claims priority to U.S. PatentApplication No. 62/316,663, filed on Apr. 1, 2016 and entitled“APPARATUS AND METHOD FOR FILTERING LIQUID PARTICLES FROM INSPIRATORYGAS FLOW OF A PATIENT BREATHING CIRCUIT AFFILIATED WITH A VENTILATORAND/OR NITRIC OXIDE DELIVERY SYSTEM,” the contents of which areincorporated herein by reference in their entirety.

FIELD

The present disclosure generally relates to the filtration or separationof liquid particles from sampled inspiratory gas flow of a patientbreathing circuit affiliated with a ventilator and/or therapeutic gasdelivery system (e.g., inhaled nitric oxide gas delivery system).

BACKGROUND

Many patients benefit from receiving therapeutic gas (e.g., nitric oxidegas) in inspiratory breathing gas flow from a breathing circuitaffiliated with a ventilator (e.g., constant flow ventilator, variableflow ventilator, high frequency ventilator, bi-level positive airwaypressure ventilator or BiPAP ventilator, etc.). To provide therapeuticgas to a patient who receives breathing gas from a ventilator, thetherapeutic gas may be injected into the inspiratory breathing gasflowing in the breathing circuit. This inhaled therapeutic gas is oftenprovided via a therapeutic gas delivery system as a constantconcentration, which is provided based on proportional delivery of thetherapeutic gas to the breathing gas. Further, a sampling system (e.g.,affiliated the therapeutic gas delivery system) may continuously draw inthe inspiratory breathing gas flow to at least confirm that the desireddose of the therapeutic gas in the inspiratory breathing gas flow isbeing delivered to the patient. For example, a sample pump may pull ininspiratory flow (e.g., in the near vicinity of the patient) to confirmthat the desired therapeutic gas concentration is in fact beingdelivered to the patient in need thereof.

One such therapeutic gas is inhaled nitric oxide (iNO). In manyinstances iNO is used as a therapeutic gas to produce vasodilatoryeffect on patients. When inhaled, nitric oxide (NO) acts to dilate bloodvessels in the lungs, improving oxygenation of the blood and reducingpulmonary hypertension. Because of this, nitric oxide is provided ininspiratory breathing gases for patients with various pulmonarypathologies including hypoxic respiratory failure (HRF) and persistentpulmonary hypertension (PPH). The actual administration of iNO isgenerally carried out by its introduction into the patient as a gasalong with other normal inhalation gases, for example, by introducingiNO, from an iNO delivery system, into the inspiratory flow of a patientbreathing circuit affiliated with a ventilator.

Separately and/or in conjunction with iNO, patients may receiveinspiratory breathing gas flow containing liquid particles (e.g.,nebulized medical solutions and suspensions, moisture from humidifiedair, etc.) and/or other particles. Although this matter in theinspiratory breathing flow may provide additional benefit to thepatient, they may contaminate the sampling system (e.g., gas analyzers)of the therapeutic gas delivery system used to confirm dosing of iNObeing delivered to the patient. Unlike the mere filtering of liquidsfrom gas, filtering these contaminates from the sampled inspiratorybreathing gas flow can be substantially difficult. Filtration designcomplexities or difficulties may include the desire for very lowinternal and external leakage, very low resistance to flow, andmaterials compatibility such that filter materials used do notadulterate the gas sample to be analyzed. Low internal and externalleakages are critical in this application, as nitric oxide (NO) ismonitored in the range of 1 to 80 parts per million (ppm) and nitrogendioxide (NO2) in the range of 1 to 5 ppm. A small external leak, forexample, may dilute the sample to be analyzed, potentially renderinginaccurate sample gas analysis. A small internal leak may allowcontaminant to pass through the filter, resulting in potentialperformance degradation of downstream pneumatic controls and/or gasanalyzer sensors, also having the potential of rendering inaccuratesample gas analysis. Low filter resistance to flow is critical as thisattribute relates directly to pump power requirements. Lower resistanceto flow enables smaller pumps consuming less power to be used, resultingin smaller, lighter, quieter medical devices. The impact of lower powercomponents can be compounded for devices requiring battery back-up,allowing for use of smaller batteries. Medical device pumps operating atlower sound pressure levels can be especially advantageous in settingssuch as the ICU, where quiet operation is critical to the clinicalstaff. Other competing physical attributes from User's perspective aredesire for longevity (e.g., infrequent filter changes would come withlarger filters) in contrast with desire for compact device (which mayrequire smaller filters). Adding complexity, the sampled inspiratoryflow is typically required throughout treatment (e.g., constant or nearconstantly sampling of the inspiratory flow just prior to, in theimmediate vicinity of, entry into the patient) to provide real time, ornear real time, confirmation of dosing during therapeutic gas deliveryto the patient.

Accordingly, at times, there is a need to filter the sampled inspiratorybreathing gas flow of liquid particles and/or other particles, forexample, to mitigate contamination of the gas sampling system. Further,there may also be other uses for an improved apparatus and method thatcan effectively filter at least these, or other, contaminants fromsampled inspiratory breathing gas flow being provided to a patient inneed thereof.

SUMMARY

Generally speaking, aspects of the present disclosure relate tofiltration apparatuses and methods to remove liquid particles from a gasstream containing humidity, water vapor, nebulized liquid or otherliquid components. Particulates may also be removed. More specifically,aspects of the present disclosure relate to filtration devices andmethods to remove liquid particles and/or particles from sampledinspiratory gas flow of a patient breathing circuit affiliated with aventilator and/or therapeutic gas delivery system (e.g., inhaled nitricoxide gas delivery system). The removal of these liquid particles and/orparticles is needed as they can contaminate the sampling systemaffiliated with the therapeutic gas delivery system.

In exemplary implementations of the present disclosure there is provideda filter apparatus for filtering liquid from a gas, comprising: ahousing having a gas inlet and a gas outlet; a first filter mediadisposed in the housing; a second filter media disposed in the housing;and a first collection basin disposed in the flow path between the firstfilter media and the second filter media, wherein a path is defined forthe gas flowing from the inlet, through the first filter media, past thecollection basin, through the second filter media, and to the outlet.

In at least some aspects of the present disclosure, the first filtermedia may be a coalescing media. The second filter media may be ahydrophobic media. The first filter media and the second filter mediamay be both mounted to, or otherwise integral to, the housing. Thefiltration pore size of the first filter media may be greater comparedwith the pore size (which also may be referred to in terms of degree ofcoarseness or fineness) of the second filter media. The first filtermedia may be configured so that droplets of liquid collected by thefirst filter media may fall (e.g., as droplets via gravity) into thefirst collection basin. The second filter media may be configured sothat droplets of liquid collected by the second filter media may fall(e.g., as droplets via gravity) into the first collection basin. Thehousing may further comprise a second collection basin, wherein dropletsof liquid collected by the second filter media may fall (e.g., asdroplets via gravity) into the second collection basin. At least someaspects of first and/or second collection basin may be defined by thehousing and/or the second collection basin may be separate from thefirst collection basin. In at least some instances the first and/orsecond collection basin may be defined by the housing, the secondcollection basin can be separate from the first collection basin.Further, in at least some instance the first and/or second collectionbasin may not be defined by the housing. In at least some instances, thesecond collection basin may not be separate from the first collectionbasin.

In at least some aspects of the present disclosure, the filtrationdensity of the first filter media may be approximately 1 micron, thefiltration density of the first filter media may be approximately [1]micron to [5] micron, the filtration density of the second filter mediamay be approximately 0.2 microns, and/or the filtration density of thesecond filter media may be approximately [0.1] micron to [0.3] micron.The first filtration media and the second filtration media may bearranged at a non-zero angle relative to each other (e.g., oblique,perpendicular, skewed, etc.), or arranged parallel to each other. Thefilter media should be oriented such that the combination of gravity andgas flow (through the media) encourages shedding of droplets intocollection basin. A vertical orientation may be preferred when comparedwith horizontal, strictly from a gravitational shedding perspective, butother orientations (e.g., vertical +/−45 degrees) would also besuccessful at shedding liquid droplets in combination with gas flowthrough the media, and would increase design flexibility.

In at least some aspects of the present disclosure, the housing definesa first aperture below the first filter media, and a second aperturebelow the second filter media, with the first and second apertures sizedso that liquid drops fall though the apertures, but splashing from thebasin to the second media is inhibited.

In other aspects, the first filter media comprises a fiberglassmaterial, and/or the second filter media comprises an expanded PTFEmaterial. The area of the first filter media may be larger when comparedwith the second filter media, as the first filter media will capturemost of the contaminants entering [such as inorganic materials (e.g.,salts from saline which may be nebulized directly or indirectly asdiluent of other nebulized medications), or organic materials (e.g.,complex hydrocarbon nebulized medications)] whereas the second filterwould be a further filtration refinement of same.

In another exemplary implementation of the present disclosure, a filterapparatus for filtering liquid from a gas is provided, comprising: afirst housing having a gas inlet and a gas outlet; a first filter mediadisposed in the first housing; a second filter media disposed in thesecond housing; and a second housing forming a first collection basindisposed in the flow path between the first filter media and the secondfilter media, wherein a path is defined for the gas flowing from theinlet, through the first filter media, past the collection basin,through the second filter media, and to the outlet.

In another example of implementations, a method of filtering liquid froma gas, comprises passing the gas through a coalescing filter media;collecting liquid filtered by the coalescing filter media to form afirst-filtered gas; passing the first-filtered gas through a hydrophobicfilter media to form a second-filtered gas; and collecting liquidfiltered by the hydrophobic media.

Other features and aspects of the disclosure will be apparent from thefollowing detailed description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present disclosure will be more fullyunderstood with reference to the following, detailed description whentaken in conjunction with the accompanying figures, wherein:

FIG. 1 illustratively depicts a cross section of an exemplary filterassembly according to an exemplary first implementation, in accordancewith exemplary embodiments of the present disclosure;

FIG. 2 illustratively depicts a cross section of an exemplary filterassembly according to an exemplary second implementation, in accordancewith exemplary embodiments of the present disclosure;

FIG. 3 illustratively depicts an exploded view of the exemplary filterassembly of FIG. 2, in accordance with exemplary embodiments of thepresent disclosure;

FIG. 4 illustratively depicts an exemplary flow diagram of a method forfiltration, in accordance with exemplary embodiments of the presentdisclosure; and

FIG. 5 illustratively depicts at least some aspects of implementation ofa filter in conjunction with a breathing gas supply apparatus, inaccordance with exemplary embodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure generally relates, to filtration of liquid from agas containing the liquid. The liquid component may be any removableliquid, such as, for example, humidity, water vapor, moisture fromhumidified air, other liquids in a vapor state, nebulized liquids,nebulized medical solutions and suspensions, etc. In someimplementations, the present disclosure describes apparatus and methodsfor such filtration in the context of delivery of therapeutic gas topatients (e.g., patients receiving breathing gas, which can includetherapeutic gas, from a ventilator circuit), and further toimplementations where a sample breathing gas is removed from aninspiratory limb to be monitored by a sampling device. This samplingdevice can be needed to continuously confirm at least dosing (e.g.,nitric oxide concentration, etc.) as well as other parameters (e.g.,nitrogen dioxide concentration, oxygen concentration, etc.). Asdiscussed further herein, filters according to the present disclosurecan be installed in between the source of breathing gas and the samplingdevice, which may reduce contamination, for example, improving operationand/or longevity of the sampling device.

The concept of filtering suspended or entrained water vapor or otherliquid components before a sample gas reaches a sampling device may bereferred to at times as a “water trap,” or “filter trap.” However, thepresent disclosure relates to some implementations that can remove morethan just water, such as, for example, nebulized liquids which may benebulized medications.

The terms liquid particles and/or particles are used herein in theirbroadest sense to encompass any and all of particles, liquid or solid,organic or inorganic, which could be in the gas flow such as, but notlimited to, nebulized medical solutions and suspensions, aerosols,moisture from humidified air, or other contaminants present in patientbreathing circuit resulting from treatments delivered via the breathingcircuit. At times the term liquid particles, particles, matter, or thelike are used individually or to refer to a common group of material tobe removed.

The terms “filter” and “filtration” are used herein in their broadestsense to encompass any and all of various types and degrees of removalor separation of liquid from gas, and may also include removal of othernon-liquid particulates if present in some cases.

FIG. 1 illustratively depicts a cross section of an exemplary filterassembly 100 according to an exemplary first implementation. An upperhousing 110 is coupled with a lower housing 112. The upper housing 110includes an inlet 114, which receives a flow of gas, which may, forexample be sample gas taken from an inspiratory limb or other portion ofa breathing gas device, as described in more detail below. The upperhousing 110 also includes an outlet 116, from which filtered gas exitsthe filter assembly 100, and the outlet 116 may be connected to adownstream component of a breathing gas device such as a gas samplingsystem or gas analyzer, as described in more detail below.

The upper housing 110 may be referred to as housing and/or include a“first stage filtration portion” 118, which may also be referred to as a“coalescing filtration portion” 118, and a “second stage filtrationportion” 120 which may also be referred to as a “hydrophobic filtrationportion 120. The first stage filtration portion supports a coalescingfilter media, or filter membrane 124 which may also be referred to as afirst stage media 124.

The first stage media 124 may be adapted to remove a range of airborneentrained liquid from the gas. The first stage media 124 may also removeparticulate matter. For example the first stage media 124 may, in someexamples remove 1.0 micron or larger droplets or particulates. The firststage media 124 may, in some examples have a glass fiber type meshconstruction creating a textured surface. As the gas passes through thefirst stage media 124, liquid droplets form in the mesh construction andcollect on the textured surface. These droplets are drawn by gravityand/or other forces (e.g., negative pressure, gravity, etc.) to theback, lower side of the first stage media 124 and fall downward off thefirst stage media 124. The droplets may pass through a first channel oraperture 126 at a lower end of the upper housing 110, and fall into acollection basin 128 and into a pool 130.

The now first-stage-filtered gas is driven, for example, by pressure(e.g., pressure differential) upward through a second channel oraperture 132 into the second stage filtration portion 120. The firststage filtered gas now passes through a hydrophobic filter media 134, orfilter membrane 134 which may also be referred to as a second stagemedia 134.

The second stage media 134 may also be adapted to remove a range ofairborne entrained liquid from the gas, and may to some extent remove0.2 micron or larger droplets or particulate matter. For example, thesecond stage media 134 may in some examples be a porouspolytetrafluoro-ethylene (PTFE) material. As the gas flows through thesecond stage media 134 droplets and particulates will be blocked frompassing through, and may simply fall via gravity and/or other forces(e.g., negative pressure, gravity, etc.) through the aperture 132 andjoin the pool 130. The gas that has passed through the second stagemedia 134 then exits the filter assembly 100 via the outlet 116.

It will be noted in this exemplary implementation, that the first stagemedia 124 may be referred to as being more coarse (less fine) than thesecond stage media 134. That is, the first stage media 124 may have apore size that is larger than a pore size of the second stage media 134.The first stage media 124 may thus be, in some examples, considered apre-filter for the second stage media 134. In so doing, the first stagemedia 124 may extend the useful lifespan of the second stage media 134,because the first stage media 124 removes droplets or particles thatwould effectively clog up or oversaturate, wet out or blind occlusion ofthe second stage media 134. In some implementations, the filtrationdensity of the first filter media may be approximately 1 micron, and/orthe filtration density of the first filter media may be approximately[1] micron to [5] microns, the filtration density of the second filtermedia may be approximately 0.2 microns, and/or the filtration density ofthe second filter media may be approximately [0.1] micron to [0.3]micron.

In this exemplary implementation, the second stage media 134 is alsoseparated from the pool 130 by a vertical distance and by the size ofthe aperture 132. These features help avoid the likelihood of liquid inthe pool 130 from splashing (e.g., during movement of the filterassembly 100) or evaporating towards the second stage media 134. Thisdegree of enhanced separation of the pool 130 from the second stagemedia 134 also may extend the useful life of the second stage media 134.The pre-filtration by the first stage media 124 may also have theadvantage of reducing the needed area and amount of material for thesecond stage media 134, compared to if the pre-filtration was notprovided.

The first stage media 124 and second stage media 134 can each be mountedat their peripheries to the upper housing 110, so that all gas must passthrough both media. Of course the first stage media 124 and second stagemedia 134 can each be mounted to the upper housing 110 at any location.At times, the first stage media 124 and second stage media 134 aredepicted and/or described as being mounted at their peripheries to theupper housing. This is merely for ease and is in no way meant as alimitation. Mounting may be accomplished via various mounting andattachment methods such as gluing, mechanical connection into a groove,compression, heat welding, vibration welding, other welding, pre-moldingor overmolding into the housing 110, and/or other attachments. The media124 and 134 may have an overmolded outer structural support that ismechanically attached to the housing 110. Gaskets may also be overmoldedor placed as part of the attachment to the housing 110. In someimplementations, the design may focus on a stricter or tightersurrounding fit for the second stage media 134, for example, since thisis the final desired filtration density.

The two stage implementation also provides for a first stage that may,in some implementations and situations, remove mostly water droplets,and a second stage that may primarily remove nebulized liquid such as adrug or saline that may be in the gas entering the filter assembly 100.

The lower housing 112 may be removably, in some implementations,attached or coupled to the upper housing 110. This may be a friction fitusing elastomeric O-rings 136 as shown in FIG. 1. There may also bethreading attaching the lower and upper housings 110 and 112. Removal ofthe lower housing 112 permits a user to empty the pooled content 130.The lower housing 112 may be transparent or translucent to assist theuser in observing when to remove and empty the liquid lower housing 112.

FIGS. 2 and 3 illustratively depict a cross section of a filter assembly200 according to a second implementation. FIG. 2 illustratively depictsa cross section of a filter assembly 200. FIG. 3 illustratively depictsan exploded view of the filter assembly 200. Some items are common, orinterchangeable in this exemplary implementation, with that of FIG. 1,and other implementations. An upper housing 210 is detachably joinedwith a lower housing 212. The upper housing includes housing portions212 a, 212 b, and 212 c. The upper housing 210 includes an inlet 214,which receives a flow of gas, which may, for example be sample gas takenfrom an inspiratory limb or other portion of a breathing gas device, asdescribed in more detail below. The upper housing 210 also includes anoutlet 216, from which filtered gas exits the filter assembly 200, andthe outlet 216 may be connected to a downstream component of a breathinggas device such as a gas sampling system or gas analyzer, as describedin more detail below.

The upper housing 210 may be referred to as housing a “first stagefiltration portion” 218, which may also be referred to as a “coalescingfiltration portion” 218, and a “second stage filtration portion” 220which may also be referred to as a “hydrophobic filtration portion 220.The first stage filtration portion supports a coalescing filter media,or filter membrane 224 which may also be referred to as a first stagemedia 224.

The first stage media 224 may be adapted to remove a range of airborneentrained liquid from the gas. The first stage media 224 may also removeparticulate matter. For example the first stage media 224 may, in someexamples remove 1.0 micron or larger droplets or particulates. The firststage media 224 may, in some examples have a glass fiber type meshconstruction creating a textured surface. The gas first passes throughan aperture 225, and a second aperture 226. As the gas passes throughthe first stage media 224, liquid droplets form in the mesh constructionand collect on the textured surface. These droplets are drawn by gravityand/or other forces (e.g., negative pressure, gravity, etc.) to theback, lower side of the first stage media 224 and fall downward off thefirst stage media 224 as depicted schematically. The droplets may passthrough the channel or aperture 226 at a lower end of the upper housing210, and fall into a collection basin 228, collecting into a pool 230.

The now first-stage-filtered gas is driven, for example, by pressure(e.g., pressure differential) sideways through a into the second stagefiltration portion 220. The first stage filtered gas now passes througha hydrophobic filter media 234, or filter membrane 234 which may also bereferred to as a second stage media 234.

The second stage media 234 may also be adapted to remove of a range ofairborne entrained liquid from the gas, and may to some extent remove0.2 micron or larger droplets or particulate matter. For example, thesecond stage media 234 may in some examples be a porous PTFE material.As the gas flows through the second stage media 234 droplets andparticulates will be blocked from passing through, and may simply fallvia gravity and/or other forces (e.g., negative pressure, gravity, etc.)into a secondary collection basin 229. The gas that has passed throughthe second stage media 234 then exits the filter assembly 200 via theoutlet 216.

It will be noted in this exemplary implementation, that the first stagemedia 224 may be referred to as being more coarse (less fine) than thesecond stage media 234. The first stage media 224 may thus be, in someexamples, considered a pre-filter for the second stage media 234. In sodoing, the first stage media 224 may extend the useful lifespan of thesecond stage media 234, because the first stage media 224 removesdroplets or particles that would effectively clog up or oversaturation,wetting out or blinding occlusion of the second stage media 234.

In this exemplary implementation, both of the first stage media 224 thesecond stage media 234 is also separated from the pool 230 by a verticaldistance and by the size of the aperture 226. These features help avoidthe likelihood of liquid in the pool 230 from splashing (e.g., duringmovement of the filter assembly 200) or evaporating towards the secondstage media 234. This degree of enhanced separation of the pool 230 fromthe second stage media 234 also may extend the useful life of the secondstage media 234. The pre-filtration by the first stage media 224 mayalso have the advantage of reducing the needed area and amount ofmaterial for the second stage media 134, compared to if thepre-filtration was not provided. In this variation, the collection basin229 that collects from the second filter media 234 is a part of theupper housing and keeps separate any drops falling from the secondfilter media 234, as compared to the lower basin 228 which collectsdrops falling from the first filter media 224.

The first stage media 224 and second stage media 234 are each mounted attheir peripheries to the upper housing 210, so that all gas must passthrough both media. This may be accomplished via various mounting andattachment methods such as gluing, mechanical connection into a groove,compression, heat welding, vibration welding, other welding, pre-moldingor overmolding into the housing 210, and/or other attachments. Forexample, sealing rings 224 a and 234 a are shown. The media 224 and 234may have an overmolded outer structural support that is mechanicallyattached to the housing 210. Gaskets may also be overmolded or placed aspart of the attachment to the housing 210. In some implementations, thedesign may focus on a stricter or tighter surrounding fit for the secondstage media 234, since this is the final desired filtration density.

The two stage implementation also provides for a first stage that may,in some implementations and situations, remove mostly water droplets,and a second stage that may primarily remove nebulized liquid such as adrug or saline that may be in the gas entering the filter assembly 200.

The lower housing 212 may be removably, in some implementations,attached to the upper housing 210. This may be a friction fit usingelastomeric O-rings 236 as shown in FIG. 1. There may also be threadingattaching the lower and upper housings 210 and 212. Removal of the lowerhousing 212 permits a user to empty the pooled content 230. The lowerhousing 212 may be transparent or translucent to assist the user inobserving when to remove and empty the liquid lower housing 212. In someimplementations, the secondary basin 229 may be not need to be emptiedduring the useful life of the assembly 200, as it may in some situationsnot collect as much liquid as the lower housing 212.

FIG. 4 illustratively depicts an exemplary flow diagram of an exemplarymethod for filtration, using a filter assembly. At process 410, samplegas is received such as via an inlet at the filter assembly. At process412, the sample gas is passed through a first stage filter, which may bea coalescing filter as described above. At process 414, liquid isremoved from the sample gas by the first stage filter. The removal maybe due to collection of droplets that fall via gravity and/or otherforces (e.g., negative pressure, gravity, etc.) into a collection basinsuch as a lower housing described above. Alternatively, the collectionbasin may be its own basin in the upper housing. At process 416, thesample gas may be passed through a second stage filter, which may be ahydrophic filter as described above. At process 418, liquid is removedfrom the hydrophobic filter, which may also fall via gravity and/orother forces (e.g., negative pressure, gravity, etc.) into a collectionbasin, which may be a lower housing as described above.

FIG. 5 illustratively depicts some aspects of exemplary implementationsof exemplary filters in conjunction with a breathing gas supplyapparatus. This exemplary implementation relates to a breathingapparatus, and does not limit the other various implementations offilter assemblies according to this disclosure. An apparatus 500 is usedwith a ventilator 510. A supply 512 of supplemental or additive gas suchas NO provides a supply to conduit 514 and leads to a valve 516 whichmay also be connected to the ventilator 510. At any stage of breathinggas supply, other additional breathing materials such as nebulized drugsmay be provided into a stream that travels via conduit 520. A controller518 may actuate valves to control the ratio of NO and nebulized drugs tothe mixture gas in conduit 520. A patient inhales the content of conduit520 which may be considered as an inspiratory limb. The patients exhaleor excess gas may be considered as an expiratory limb conduit 522.

In this example, a conduit 524 is in fluid communication with theinspiratory limb and may be referred to as a sample gas line. A filtertrap 526 receives some or all of the sample gas. This filter trap 526may correspond to a filter assembly such as described above. After beingfiltered by the filter trap 526, the gas is passed to a gas samplingsystem 528, and may exhaust via exhaust outlet 530.

In some examples herein, the sample gas line is connected directly tothe water trap assembly. This direct connection can prevent unfilteredsample gas from contacting reusable material with the gas samplingsystem. The entire water trap assembly may be also disconnectable and insome implementations disposable.

In addition to variations and implementations described herein, the gasanalyzer may include a sensor such as a gyroscopic sensor to determineif water and/or other materials are being filtered to a desired degree,and could in some implementations further indicate by sound or visuallythat the water trap is not properly operating to a desired degree.

It will be appreciated that, among other aspects, the present disclosurein some implementations relates to a filter apparatus for filteringliquid from a gas, the apparatus having a first housing having a gasinlet and a gas outlet; a first filter media disposed in the housing; asecond filter media disposed in the housing; and a second housingforming a first collection basin disposed in the flow path between thefirst filter media and the second filter media, so that a path isdefined for the gas flowing from the inlet, through the first filtermedia, past the collection basin, through the second filter media, andto the outlet. The present disclosure also relates to a method ofpassing a gas through a coalescing filter media and through ahydrophobic filter media.

The filter assemblies and methods described herein, may in someimplementations be useful to filter liquid (and/or particulates) from asample gas from a patient breathing apparatus for analysis by a gassampling system. However, other applications for the filter assembliesand methods may arise.

Other implementations are contemplated. For example, in FIGS. 1 through3, the inlet and the outlet are shown as part of the upper housings.However, in some variations, the inlet and/or the outlet may be providedon the lower housing or basin.

The foregoing detailed descriptions are presented to enable any personskilled in the art to make and use the disclosed subject matter. Forpurposes of explanation, specific nomenclature is set forth to provide athorough understanding. However, it will be apparent to one skilled inthe art that these specific details are not required to practice thedisclosed subject matter. Descriptions of specific applications areprovided only as representative examples. Various modifications to thedisclosed implementations will be readily apparent to one skilled in theart, and the general principles defined herein may be applied to otherimplementations and applications without departing from the scope ofthis disclosure. The sequences of operations described herein are merelyexamples, and the sequences of operations are not limited to those setforth herein, but may be changed as will be apparent to one of ordinaryskill in the art, with the exception of operations necessarily occurringin a certain order. Also, description of functions and constructionsthat are well known to one of ordinary skill in the art may be omittedfor increased clarity and conciseness. This disclosure is not intendedto be limited to the implementations shown, but is to be accorded thewidest possible scope consistent with the principles and featuresdisclosed herein.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the methods and systems ofthe present description without departing from the spirit and scope ofthe description. Thus, it is intended that the present descriptioninclude modifications and variations that are within the scope of theappended claims and their equivalents.

It will be understood that any of the steps described can be rearranged,separated, and/or combined without deviated from the scope of theinvention. For ease, steps are, at times, presented sequentially. Thisis merely for ease and is in no way meant to be a limitation. Further,it will be understood that any of the elements and/or embodiments of theinvention described can be rearranged, separated, and/or combinedwithout deviated from the scope of the invention. For ease, variouselements are described, at times, separately. This is merely for easeand is in no way meant to be a limitation.

The separation of various system components in the examples describedabove should not be understood as requiring such separation in allexamples, and it should be understood that the described components andsystems can generally be integrated together in a single packaged intomultiple systems and/or multiple components. It is understood thatvarious modifications may be made therein and that the subject matterdisclosed herein may be implemented in various forms and examples, andthat the teachings may be applied in numerous applications, only some ofwhich have been described herein. Unless otherwise stated, allmeasurements, values, ratings, positions, magnitudes, sizes, and otherspecifications that are set forth in this specification, including inthe claims that follow, are approximate, not exact. They are intended tohave a reasonable range that is consistent with the functions to whichthey relate and with what is customary in the art to which they pertain.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present invention without departing from the spirit andscope of the invention. Thus, it is intended that the present inventioninclude modifications and variations that are within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A filter apparatus for filtering liquid from agas, comprising: a housing having a gas inlet and a gas outlet; a firstfilter media disposed in the housing; a second filter media disposed inthe housing; a first collection basin and a second collection basindisposed in a flow path between the first filter media and the secondfilter media, wherein a path is defined for enabling the gas to flowfrom the gas inlet, through the first filter media, past the firstcollection basin, through the second filter media, and to the gasoutlet, and wherein droplets of liquid collected by the second filtermedia may fall via gravity into the second collection basin.
 2. Theapparatus of claim 1, wherein the second collection basin is defined bythe housing, separate from the first collection basin.
 3. The apparatusof claim 1, wherein the first filter media is a coalescing media.
 4. Theapparatus of claim 3, wherein the second filter media is a hydrophobicmedia.
 5. The apparatus of claim 1, wherein the second filter media is ahydrophobic media.
 6. The apparatus of claim 1, wherein the first filtermedia and the second filter media are both mounted, respectively, to thehousing.
 7. The apparatus of claim 1, wherein the first filter media isconfigured so that droplets of liquid collected by the first filtermedia may fall via gravity into the first collection basin.
 8. Theapparatus of claim 7, wherein the second filter media is configured sothat droplets of liquid collected by the second filter media may fallvia gravity into the first collection basin.
 9. The apparatus of claim1, wherein the second filter media is configured so that droplets ofliquid collected by the second filter media may fall via gravity intothe first collection basin.
 10. A filter apparatus for filtering liquidfrom a gas, comprising: a first housing having a gas inlet and a gasoutlet; a first filter media disposed in the first housing; a secondfilter media disposed in the second housing; and a second housingforming a first collection basin disposed in the flow path between thefirst filter media and the second filter media, wherein a path isdefined for the gas flowing from the inlet, through the first filtermedia, past the collection basin, through the second filter media, andto the outlet.
 11. The apparatus of claim 10, wherein the first filtermedia is a coalescing media.
 12. The apparatus of claim 11, wherein thesecond filter media is a hydrophobic media.
 13. The apparatus of claim10, wherein the second filter media is a hydrophobic media.
 14. Theapparatus of claim 10, wherein the first filter media and the secondfilter media are both mounted, respectively, to the housing.
 15. Theapparatus of claim 10, wherein the first filter media is configured sothat droplets of liquid collected by the first filter media may fall viagravity into the first collection basin.
 16. The apparatus of claim 15,wherein the second filter media is configured so that droplets of liquidcollected by the second filter media may fall via gravity into the firstcollection basin.
 17. The apparatus of claim 10, wherein the secondfilter media is configured so that droplets of liquid collected by thesecond filter media may fall via gravity into the first collectionbasin.
 18. A method of filtering liquid from a gas, comprising: passingthe gas through a coalescing filter media; collecting liquid filtered bythe coalescing filter media to form a first-filtered gas; passing thefirst-filtered gas through a hydrophobic filter media to form asecond-filtered gas; and collecting liquid filtered by the hydrophobicmedia.